When moving an article by means of a motor, it may be required to stop the article precisely at a desired position. For that purpose, an inverter may be used in combination with an AC motor, or a dedicated control apparatus may be used with a servo motor. Furthermore, an encoder or the like is usually used in association with the motor for determining the number of rotations of the motor for such position control.
Because of the use of encoders, such motor control is expensive. Also, an expensive programmable logic circuit is required for giving commands to the inverter or the servo motor control apparatus. In addition, for modifying the contents of the programmable logic circuit, a writing device and external content-modifying switches must be used.
An object of the present invention is to provide a motor control apparatus which does not require such encoder and other associated apparatuses mentioned above, and, therefore, can be manufactured at a low cost.